Endocrinology, Vol 104, 438-442, Copyright © 1979 by Endocrine Society
Hypoandrogenism and abnormal regulation of gonadotropin secretion in rats fed a low protein diet
AR Glass, R Mellitt, RA Vigersky and RS Swerdloff
The function of the hypothalamic-pituitary-testicular axis was evaluated in
rats fed a low protein diet for 4 weeks beginning at 21 days of age.
Compared to control, the low protein group had decreased seminal vesicle
and prostate weights as well as decreased testicular testosterone output in
vitro, although serum testosterone was not different. The low protein group
showed no consistent alterations in serum LH (basal, post-LHRH, and
postcastration) compared to control although serum FSH (basal and
post-LHRH) was lower in the low protein group. Despite this lower basal
FSH, the low protein group had supranormal serum FSH after castration.
Seminiferous tubule diameter and testicular histology were normal in the
low protein group although testicular androgen-binding protein was absent.
Testicular androgen- binding protein was also undetectable in a modestly
food-restricted control group which had normal testicular size, testicular
histology, androgen output, and serum FSH. This finding suggests that loss
of testicular androgen-binding protein may be a sensitive sign of
undernutrition. We conclude that rats fed a low protein diet have
hypoandrogenism, normal testicular histology, and supranormal FSH after
castration despite subnormal basal FSH. The latter combination suggests
overproduction of an FSH inhibitor of testicular origin.
